Bucket spinning process



Patented Oct-.17, 1933 UNITED STATES PATENT OFFICE BUCKET SPINNING PROCESS No Drawing. Application June 25, 1930 Serial No. 463,825

2 Claims.

This invention relates to the art'of producing artificial thread. More particularly, it relates to the production of artificial thread by centrifugal spinning or the bucket spinning process.

One of the well known processes of producing artificial thread from viscose consists in ejecting the spinning solution into a coagulating and/0r regenerating bath from whence it is drawn by a godet wheel and directed into a vertically reciprocating funnel, which guides it into a rotating collection device, such as a bucket, where it is wound by centrifugal action to form a cake. The collection device, as previously mentioned, consists of a cylindrical bucket usually formed of or lined with an acidresisting material and is provided with small holes in the side thereof to permit the passage of air and the exit of the excess liquor carried over by the thread. It is mounted on a spindle and is usually rotated by motion transmitted through a friction drive. Adjacent the top the bucket is provided with a shoulder on which is seated a removable centrally apertured cover which is held in place by some resilient means, such as a resilient spring or ring disposed in a groove in the wall above the shoulder. The funnel guide which conducts the thread into the bucket passes through the central aperture.

In the operation of these methods, the bucket is rotated at a speed of from 5,000 to 6,000 B. P. M. The thread is drawn into the bucket and thrown against the wall thereof or layers of previously wound hread and there retained by the centrifugal force produced by the rotation of the bucket. The centrifugal force also acts on the air in the bucket and tends to force or throw it against the sides of the bucket. At the early stage of the spinning cycle, the air is forced through the perforations in the side of the bucket and air is drawn in through the aperture of the cover, thus setting up an air circulation. As the cake builds up, the amount of air which passes through it and the perforations becomes decidedly less and the air pressure within the bucket is relieved by air passing out through the aperture in the cover. United States Patent No. 702,382 discloses that as the cake built up and the air currents changed, the threads were swept out of the bucket, resulting in entanglement and degradation. He showed that a cover so changed the air currents that a good cake formation resulted, and this covered bucket has been the standard of the industry up to this time.

Another factor in the cake formation is the peripheral speed of the winding-on surface of the cake. At the beginning of the spinning, the thread winds on to the side of the bucket and so acquires the peripheral speed of the interior wall of the bucket. Since the cake is formed by successive layers of thread, laid inwardly, the peripheral speed of the winding-on surface becomes much less than that of the bucket resulting in the production of thread of difljerent qualities. In the practice in vogue today, the cake formation is continued until some arbitrary point, at which time the spinning is stopped and the bucket together with the cake is removed. The empty bucket is then mounted in position and spinning is resumed. Such a process results in a very large number of cakes of thread which, since each cake must be subsequently processed, results in an expensive procedure.

We have found that, when the peripheral speed of the winding-on surface is increased, as for instance by increasing the diameter of the bucket and/or the speed. of rotation of the bucket, the windage in the bucket becomes so large and the cake formation so good that a cover may be dispensed with and, in spite of the increased opening provided for the air, the thread remaining in the bucket is wound in an orderly arrangement.

It is therefore an object of this invention to provide a method of producing artificial threads by the bucket spinning process, wherein a thread is centrifugally wound at a high rate of speed in a coverless bucket.

Another object of this invention is to pro- .vide a method of producing artificial threads by the bucket process wherein the thread is centrifugally wound in a coverless bucket rotated at a high speed, such as for instance in excess of 7,000 R. P. M.

Other objects will appear from the following description and appended claims.

According to this invention, a viscose solution is spun in the usual manner into a coagulating and/or regenerating bath from whence it is drawn by means of a godet wheel and directed into a collection device, such as a cover-less bucket, in the usual manner. The bucket employed in the method constituting this invention may be constructed similar to those used in the well known bucket spinning process. Of course, since the bucket is used coverless, the shoulder and groove adjacent the top of the bucket maybe eliminated, if desired. Any means for rotating the bucket may be used but, since the bucket is rotated at very high speed, positive drives are preferable. As previously mentioned, the essential feature of this invention is to carry 'out the winding step at such a speed that the even though no cover has been used. It is, of

course. within the purview of this invention to utilize a smaller bucket, for instance, a bucket having a diameter of five inches operated at the speeds previously mentioned.

The elimination of the cover in addition to providing a cake which has satisfactory properties also prevents any unbalancing of the bucket caused by irregularities in the cover and in the cover-retaining means and which is quite substantial at the high speeds. The use of a coverless bucket also permits the (letting of the cakes without removal of the bucket from the setupandthuseliminatesthedsmaseusuallyoc- Though this invention has been described and I speciflcreference to the manufacture of viscose thread, itis not restricted thereto, since the principles thereof are applicable to the production of any variety of artificial thread.

Since it is obvious that various modifications may be made in the specific details hereinabove described, the invention is not restricted thereto except as defined in the appended claims.

We claim: a 1. In the manufacture of artificial thread b the bucket processthe step of winding the thread in a coverless bucket rotated at such a speed that the peripheral speed of the winding-on surface thereof at the beginning of the winding operation is in excess of 9100 feet per minute.

2. In the manufacture of artificial thread by the bucket process the step of winding the thread in a coverless bucket having an' average internal diameter of at least 5.9 inches and rotated at a speed not less than 7,000 R P. M.

. PAUL E. HARRISON.

WILLIAM V. S'IERNBERGER. 

